Innovative Materials Testing Technologies, Inc. Air Force Research Laboratory Session 27 - REMOTE FIELD EDDY CURRENT MILITARY AND COMMERCIAL PLATFORM APPLICATIONS

Sun, Brausch, LaCivita and Sanders- 9th Joint FAA/DoD/NASA Conference on Aging Aircraft

Innovative Materials Testing Technologies, Inc.

Air Force Research Laboratory

Session 27 - REMOTE FIELD EDDY CURRENT MILITARY AND COMMERCIAL PLATFORM APPLICATIONS

REMOTE FIELD EDDY CURRENT MILITARY AND COMMERCIAL PLATFORM APPLICATIONS

Yushi Sun - Innovative Materials Testing Technologies, Inc.

John C. Brausch, Kenneth LaCivita, Lt William Sanders

- U. S. Air Force Research Laboratory

1





Acknowledgements

The authors would like to express their appreciation and great thanks to Jeff A. Register and Michael J, Fortman, Northwest Airlines[1], and Captain D. J. Butcher, Canadian Air Force, for their providing the test samples, test requirements and comments to IMTT.

The authors would like also to express their appreciation and great thanks to Dr. Ward D. Rummel, D&W Enterprises, LTD, for his careful view and valuable comments to this paper.

[1] Jeff A. Register and Michael J, Fortman were with Northwest Airlines when they were involved in the work, Application No. 6, stated in this paper. Now they are working with Aerotechinics NDT, Inc.





2

Introduction

• Current Tend of Utilizing Composite-Metal Structure in New & Old Airplanes

• New Demand to NDT – Inspection of Metals through Composite

• FG_RFEC Technique is Characterized by its Deep Penetration

• Purpose of This Paper:

Introduce New Applications of FG_RFEC Technique in Inspection Metals Through Composite and others





3

Six Examples

1. Detection of aluminum layer crack through 1.5” of polycarbonate

2. Detection of aluminum layer crack through 0.52” – 0.90” graphite epoxy composite

3. Detection of titanium layer crack through 0.25” – 0.50” graphite epoxy composite

4. Detection of cracks on titanium layer through graphite epoxy composite and suppression of sealant groove signals

5. Detection of crack 0.50” below aluminum structure surface (simulating CC130 Structure)

6. Detection of fine surface and subsurface cracking on curved steel surface (Airbus A-320 Landing Gear Structure)





4

Probes





5

SSEC System





6

Example #1: Detection of aluminum layer crack through 1.5” of polycarbonate

Three 7”×13” polycarbonate pieces with thicknesses:567-007 – 0.567”;483-007 – 0.483”442-007 – 0.442”

A 9.0”×1.25”×0.20” aluminum strip attached below

Two layersOne layer Three layers

Probe

Aluminum StripProbe

Strip under inspection

Strip under inspection

Probe





7

T = 0.567”

T = 0.567”





8





9

Maximum Y = 0.1215v

f = 200Hz

Three Layers, T ~ 1.50”





10

Example #2: Detection of aluminum layer crackthrough 0.52” – 0.90” graphite epoxy composite

Specimens

T = 0.520” or 0.896”





T = 0.520”

Set #1 Set #2





T = 0.896”

Set #1 Set #2





Example #3: Detection of titanium layer crack through 0.25” – 0.50” graphite epoxy composite

Crack sizes: 0.250”, 0.500” and 0.750”

Composite Thickness: 0.250”, 0.333” and 0.500”

Specimens





0.3 0.4 0.5 0.6 0.70

0.05

0.1

0.15

0.2

0.25

Sig

na

l M

ag

nitu

de

[v]

Ti Sample Crack Length [inch])

With Composite Sample #2Thickness = 0.250”



Summary of Test Results





Example #4: Detection of Ti layer crack through graphite epoxy composite and suppression of sealant groove signals

Specimen





Rotational Probe RF4 ROT Scanning around Fastener





Case 1: Horizontal Groove is on top

Case 2: Vertical Groove is on top

Pickup

Pickup





Example # 5: Detection of crack 0.50” below aluminumstructure surface Using Rotational Probe (CC130)





Example #5: Detection of fine surface and subsurface cracking on curved steel surface (A-320 Landing Gear)

0.030”×0.030” upper EDM

0.080” hidden hole drilled from top cut section

0.030”×0.030” lower EDMPossible crack area





Rf2 V.3 Sliding Probe + Specially Designed Holder





Hidden holeF = 1.0 kHz

Lower 0.030”×0.030” EDMF = 40.0 kHz

Upper 0.030”×0.030” EDMF = 40.0 kHz





Summary

1. Metallic layer cracks underneath thick composite layer are detectable using FG_RFEC technique – sliding probes or rotational probes;

2. Groove signal can be effectively suppressed using a band-pass filter;

3. FG_RFEC technique working with SSEC system is capable of detecting deeply hidden cracks and fine surface and subsurface cracking with high sensitivity.

4. The next step is to assess existing or new inspections, now available to our industry, to find the right fit and application of this advanced technology.

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Innovative Materials Testing Technologies, Inc. Air Force Research Laboratory Session 27 - REMOTE FIELD EDDY CURRENT MILITARY AND COMMERCIAL PLATFORM APPLICATIONS